Pipeline valves must have a valve element therein that admits a "pig" or cleaning device to travel therethrough in order to enable the interior of the pipeline to be cleaned from time to time. Accordingly, in the past, it has been necessary to employ a very large valve housing in order to make available a valve element having a flow passageway therethrough of a diameter equal to the nominal diameter of the pipeline. It would be desirable to have made available a valve device that can be series connected into a flow line, that has a valve element therein that receives a cleaning pig therethrough when the valve element is in the open position.
Furthermore, it would be desirous to have a check valve device associated with the valve means that permits unobstructed flow in one direction through the valve device and which prevents flow in the opposite direction. The above desirable valve structure is obtained in accordance with the present invention.